This invention relates to the positioning of engine gaskets between communicating engine parts adapted to be mechanically fastened together, particularly during assembly line processes. More particularly, the invention relates to the design of positioning devices, variously called grommets, bushings, eyelets, and ferrules, utilized to assist in accurate placement of a gasket on one of the parts to be joined.
Numerous devices have been provided for positioning gaskets on engine parts during assembly. A number of devices have included plastic members, some of which are shaped like inverted Christmas trees having tapered bodies for positive placement. Most of such devices are separate from the gasket and are typically inserted after the gasket has been laid over the surface of the engine part. Some of the devices are made of metal, and in at least one case, the positioning device is permanently fixed to the gasket at the time of manufacture. All of the foregoing devices, however, have in common the aspect of being designed to frictionally engage a bore within the engine part to which the gasket is to be applied. Due to tolerance variations in gasket sizing and bore location, there is a certain amount of gasket distortion not readily accommodated by these positioning devices. Ideally, positioning devices would be designed to yield or shift in associated engine bores to permit gaskets to lay flat and to hence minimize distortion. Upon securement of mating parts, a distorted gasket is more susceptible to leakage, and thus likely to result in engine failure.